Bally Flip Flop lower left flipper button switch NO, is always closed. Game will not start unless I put a piece of paper between the blades of that switch. When I start a game, no left flippers, and there is a humming sound coming from within the cabinet.
Could a bad flipper coil be the cause? It looks pretty fried and Digital multi meter continuity reads: 1

With game is in play with left flipper switch insulated open, there is an audible humming sounds like it's coming from transformer which increases when pressing Right flipper button.

Problem is as soon as I press the left flipper button to close the switch, the Game Over trip reverts to Unlatched and game ends

Ok disconnected wires from left lower flipper coil. Game Over relay behaving. Right flippers working but a bit chattery (especially top right flipper) I assume the left flipper coil must be bad